The thing about US antitrust law is that you still have to prove harm to consumers, and that is where I feel the DOJ will have their work cut out for them. At best, an argument can be made that developers are the ones being harmed, but IIRC, a prior lawsuit has already ruled that developers are not eligible to sue Apple in the US because Apple deals with customers, not with them. And it's hard to make a case that consumers are being actively harmed by the superior user experience that the Apple ecosystem affords.
I guess I still don't see it as being anti-competitive. Yes, Apple is giving themselves an advantage over everyone else by reserving certain features only for their products, and that's kinda their whole selling point. Companies like Tile won't be happy, but I feel there's a difference between "unfair" and "not to my advantage". Likewise, maybe I buy AirTags because I trust that they come from Apple and maybe I don't trust third parties having the same access to my find my network?
And remember - everyone was convinced that Apple's closed ecosystem approach wouldn't work, and Apple proved the haters all wrong, and we are talking about regulating a company with only 20% market share worldwide.
I doubt a lawsuit in the early 2000s would have yielded any results. It's telling that the EU had to go through all that trouble of crafting new laws in order to reign Apple in (implying that Apple had not broken any of the original laws), and unless the US can get its act together to do the same, I am cautiously optimistic that it won't yield any results today either.
Remember - just because many of you here don't like how Apple runs their business doesn't mean they are necessarily breaking any laws.